In this project, various aspects of immunological reactions to haptens on autologous carriers will be studied. Haptens (DNP or NIP) will be conjugated to mouse gamma globulin or mouse serum albumin in vitro or mice will be skin painted with DNFB to induce delayed hypersensitivity. The role of the thymus cells in initiating an immune response to these haptens will be investigated. Thymectomized or sham thymectomized mice will be primed to these antigens and the DNA synthetic response and antibody response measured. Tolerance induction to hapten in T- and B-cells will be assessed. Attempts will be made to transfer tolerance to normal mice with cells tolerized in vivo with DNBSO3. This will give us an insight in the mechanism of tolerance in T- and B-cells, whether it is antibody mediated or involves receptor blockade or loss of a clone of cells.